THE THREAT OF INVASIVE PLANTS IN NATIVE FORESTS OF EASTERN POLYNESIA

Jean-Yves Meyer

Eastern Polynesia, a phytogeographical subregion of Polynesia in the Pacific
Ocean, comprises the archipelagoes of the Cook Islands, the Australs, the
Society, the Tuamotu, the Marquesas, the Gambier, the Pitcairn Islands, and Rapa
Nui which is the easternmost inhabited island of Polynesia. These tropical to
subtropical oceanic islands are among the most remote in the world. Because of
this strong geographic isolation and their small terrestrial surface, their
native flora is impoverished, disharmonic, and with a low number of endemic
genera. However, some high volcanic islands within these archipelagoes display a
great diversity of habitats and a highly endemic flora with striking cases of
adaptative radiation. Most of these endemic taxa are restricted to montane rain
forests and cloud forests. The main threat to these upland wet forests is not
habitat destruction by man, or over-grazing by large mammals, but rather the
insidious biological invasion of alien plants. Native forests of Eastern
Polynesia are threatened by the same aggressive introduced species (e.g Psidium
cattleianum and Syzygium jambos in Pitcairn and the Marquesas lslands,
or Ardisia elliptica and Cestrum nocturnum in Rarotonga and the
Society Islands). Therefore, one of the highest priority for the long-term
conservation of these native upland forests should be given to the study
(invasion dynamics and ecological impacts) and control (strategy and methods) of
the current invasive plants, and to the early detection and eradication of
potential plant invaders.

Abstract from: 43rd Symposium of the International Association for Vegetation Science, July 23-28, 2000, Nagano,
Japan.